High Altitude Derate; Electrical Connections - Lennox LGH150H Installation Instructions Manual

High Altitude Derate

Locate the high altitude conversion sticker in the unit
literature bag. Fill out the conversion sticker and affix next
to the unit nameplate.
Refer to table 2 for high altitude adjustments.
TABLE 2
HIGH ALTITUDE DERATE
Altitude Ft.*
2000-4500
4500 And Above Derate 2% / 1000 Ft. Above Sea Level
*Units installed at 0-2000 feet do not need to be modified.
NOTE ‐ This is the only permissible derate for these units.

Electrical Connections

POWER SUPPLY
A-Wiring
Route field wiring in conduit between bottom power entry
disconnect. See figure 13. This does not supersede local
codes or authorities having jurisdiction.
FIELD WIRE ROUTING
SIDE ENTRY
KNOCKOUTS
SEAL
WATERTIGHT
FIGURE 13
Gas Manifold Pressure
See Unit Nameplate
OPTIONAL
120V GFI
MAKE-
UP BOX
RUN FIELD
WIRING IN
FIELD PRO­
VIDED CONDUIT
BOTTOM
POWER ENTRY
Do not apply power or close disconnect switch until
installation is complete. Refer to start-up directions.
Refer closely to unit wiring diagram.
Refer to unit nameplate for minimum circuit ampacity
and maximum fuse size.
1- 230/460/575 volt units are factory wired. For 208V
supply, disconnect the orange wire (230V) at all
control power transformer(s). Reconnect the red
wire (208V). Tape the exposed end of the 230V
orange wire.
2- Route power through the bottom power entry area.
On gas units or units with electric heat, connect
power wiring to TB2. On cooling only units,
connect power to F4. If unit contains an optional
factory-installed circuit breaker or disconnect
switch, connect line voltage to CB10 or S48. See
unit wiring diagram.
3- Connect separate 120v wiring to optional GFCI
outlet. Route field wiring in conduit between bottom
power entry and GFCI. See figure 13.
B-Unbalanced Three-Phase Voltage - VFD Units Only
Units equipped with an optional inverter (VFD) are
designed to operate on balanced, three-phase power.
Operating units on unbalanced three-phase power will
reduce the reliability of all electrical components in the
unit. Unbalanced power is a result of the power delivery
system supplied by the local utility company.
Factory-installed inverters are sized to drive blower
motors with an equivalent current rating using balanced
three-phase power. When unbalanced three-phase
power is supplied; the installer must replace the existing
factory-installed inverter with an inverter that has a higher
current rating to allow for the imbalance. Use table 3 to
determine the appropriate replacement inverter.
Factory-Installed Inverter HP
2
3
5
Page 11
TABLE 3
INVERTER UP-SIZING
Replacement Inverter HP
5
7-1/2
10